This invention relates to a golf club, to a shaft used therewith and to a method of making the shaft. This invention particularly relates to a golf club, a shaft therefor which is structured in a butt end section, a central section and a tip end section thereof to enhance the playability of the club from the standpoint of stresses and flexure profile. This invention also particularly relates to a method of making the shaft.
A golf club includes a shaft having a tip end section and a butt end section with a club head mounted on the end of the tip end section and a hand grip mounted on the butt end section. The shaft is further formed with a central section which extends between inboard ends of the butt end section and the tip end section.
The shaft is a critical part of the club and the structural characteristics of the shaft play an important role in the results obtained by a golfer in the playing of the game of golf. Shafts for golf clubs are typically made from a composite non-metallic material or a metal such as, for example, steel.
In one technique of making steel or metal shafts, a round tube having a uniform thickness from one end to the other is processed through a taper press, in a die sink process, to form a generally cylindrical butt end section, a tapered tip end section and a stepped configuration in a central section of the shaft between the butt and tip end sections. Shafts of this type typically have a specified thickness at the outboard end of the tip end section with prescribed decreases in the thicknesses to the outboard end of the butt end section thereof. Thus, the heaviest portion of the shaft is located in the tip end section, where the wall thickness is the greatest, and the lightest portion in the butt end section where the wall thickness is the smallest.
This results in a golf club shaft having stresses which are significantly high in the butt end section, or grip, when the club is used in the playing the game of golf. The resultant placement of these stresses could have a deleterious effect on the golfer's playing of the game. In addition, the resultant moment per flexural rigidity of such a shaft, and the club formed thereby, is significantly high at a point along the shaft generally in the area of the butt end section, or grip, of the club. This results in a flexure profile wherein the location of the initial flexure point of the shaft, and the club, is in the area of the butt end section, or grip. When a golfer uses a golf club of this type, the club head is at such an angle upon impact with the ball that the optimum launch angle of the ball may not be attainable.
Consequently, there is a need for a shaft, and a golf club, which locates the stresses away from the grip during the swinging of the club and upon impact with the ball. Further, there is a need for a shaft, and a golf club, having a flexure profile which provides the golfer with a facility for obtaining improved distance of travel for the ball when impacted by the club head.